Black UI theme

[codenyte]

Is your feature request related to a problem? Please describe.
The dark theme doesn't make the background fully black, but rather just a dark shade of gray.

Describe the solution you'd like
A pitch black theme, in addition to the normal dark theme. This is really useful on OLED screens, as these can achieve true blacks, which means that the background can be completely dark without emitting any light. This contrast makes colors pop more and text appear clearer, reducing eye strain and improving the overall viewing experience. Theoretically, this could also save battery life, since a true black background does not require any backlight to be turned on.

Describe alternatives you've considered
Using Material You and Repainter, but this requires root access.

Additional context
Black theme in Suyu Emulator:

As you can see, the background is actually black (#000000).